PROJECT SUMMARY/ABSTRACT Almost one-third of breast cancer survivors report an inability to fully participate in vocational, social, physical, and instrumental activities of daily living. Breast cancer survivors who report lower participation in these activities report lower quality of life and greater depression, and are at risk for shortened survival. The long- term goal of this research is to address the absence of scalable, accessible, evidence-based interventions that improve cancer survivors' participation in life roles and activities. The objective of this R01 from a new investigator is to test a telephone-delivered, Behavioral Activation/Problem-solving (BA/PS) intervention designed to directly foster activity participation. The BA/PS intervention is a theory-based intervention that was developed over three pilot studies. Over nine sessions, survivors increase or enhance their participation in life roles and activities by setting, adjusting, and achieving goals that incrementally adapt their activities and environments and enhance their personal capacity. This application proposes a randomized controlled trial (RCT) to evaluate the efficacy of BA/PS for improving activity participation as compared to an attention control condition within a sample of 300 breast cancer survivors reporting reduced functioning after completing cancer treatment. In order to maximize diversity, the study will be conducted at two National Cancer Institute- designated Comprehensive Cancer Centers: Norris Cotton Cancer Center at Dartmouth (NH) and the University of Alabama at Birmingham Comprehensive Cancer Center (AL). The study will address three specific aims: (1) To evaluate the effect of BA/PS on participation/productivity in social roles and activities (primary outcome); (2) To evaluate the effect of BA/PS on quality of life; (3) To evaluate the effect of BA/PS on the outcomes of coping, goal adjustment, and distress. The trial is designed to test whether the BA/PS intervention affects the slope of functional recovery over time. The outcome variables listed above are measured at eight, 20, and 44 weeks after study enrollment, allowing the exploration of both immediate and sustained intervention effects. The theory-driven, standardized approach is innovative because it directly promotes resumption of valued activities as identified by each survivor. The telephone delivery method increases the accessibility of the intervention and has the ability to drive the field forward, in contrast to clinic- based interventions that only meet the needs of those survivors with the time and ability to return to an outpatient setting. The proposed research is significant because it helps breast cancer survivors develop strategies to enhance productivity at home, in the workplace, and in the community, and to create sustainable lifestyle changes that foster health, participation, and functional well-being. As such, the knowledge gained from this study has the potential to advance the mission of the Office of Cancer Survivorship (of the National Cancer Institute) by reducing disability and improving the quality of life of cancer survivors.